From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DBDF638A72B; Mon, 8 Jun 2026 14:24:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780928662; cv=none; b=MryxTjjiIaFZclZHBTgw3OxNYl3jUq9tcPo0GLhDLEnp0ZvyEYLVftKLuvupeEyE/QtJWAGJ5WmLl3ot2rZFG/0vMD+HVD1yos0FlZNiXqyVzvU+vgq/7tU3fb0tbEZVuaBH1h7N43wV6+wZeivlVnZHjXtT5diWGq+lVr0Ommg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780928662; c=relaxed/simple; bh=QRE7yBxmt6dZDSBRemCh6llijh3yzWyacNI7zuU+HTw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=i8j22oY+twjH9+eeDn9wgUPFI9d1ebBh437zmmP5eJx+ycO6aC6rkwdr7qr0giXI7S3xEcFk8VoUs4CNoSLChZ0zdzsRz+Sr75elrMmS+kPtObdFok2nOQX80AWK+ELypyUfXiylc98w8+imNZ568sxTboNsQcykUWEhFPgDtfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f77AGlaS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f77AGlaS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75C0F1F00893; Mon, 8 Jun 2026 14:24:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780928661; bh=cjX8+061TbVjwdZkrMpGGF5UrC/j9HGWiAY7267pDNU=; h=From:To:Cc:Subject:Date; b=f77AGlaS6HBVxqhZkkJaK6b99hh1j5WLUqwlOcQ4XHW6uh23v4gv3Axcvhfndj9rA fm623nHWTCJHysS1H1cXErOtZ6ooF6tjKuANecAJVYPssg25xjy6XY7/B7Q2YKzwMA eya8VzYYnbDujPfFUHYWWn++cY4jOZUCzfOQEbYJKW6WI5UZA0Nh5nQQ3+WlnYnBaU 5QasU3GPek1KhPSyQJ3KkQsg24UACh4cDz6F5Tuldh7J10Tpl5TSziNCrENGJeI4dS vxRklYAiC8owVwkeDW4pkiENIsSKAPZcty9tPgFnnro/M54q5zUoDfPJLJi7egOwZp Xoor4wX2gLUyg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Mathieu Desnoyers Cc: Jonathan Corbet , Shuah Khan , Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [RFC PATCH 0/7] tracing/probes: Add more typecast features Date: Mon, 8 Jun 2026 23:24:16 +0900 Message-ID: <178092865666.163648.10457567771536160909.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Hi, Here is a series of patches to introduce more typecast features to probe events, which includes 1. expanding BTF typecast to fprobe and kprobe events, 2. introducing container_of like typecst option, 3. supporting nested typecast, 4. adding $current special variable support, 5. adding per-cpu dereference support, 6. adding a testcase to check typecasts. Steve introduced BTF typecast feature for eprobe[1]. This series extends it and add more options: 1. Expanding BTF typecast to kprobe and fprobe. (currently only function entry/exit) 2. Introduce container_of like typecast. This adds a "assigned member" option to the typecast. (STRUCT,MEMBER)VAR->ANOTHER_MEMBER This casts VAR to STRUCT type but the VAR is as the address of STRUCT.MEMBER. In C, it is: container_of(VAR, STRUCT, MEMBER)->ANOTHER_MEMBER 3. Support nested typecast, e.g. (STRUCT)((STRUCT2)VAR->MEMBER2)->MEMBER the nest level must be smaller than 3. 4. Add $current variable to point "current" task_struct. This is useful with typecast, e.g. (task_struct)$current->pid 5. per-cpu dereference support. +CPU(VAR) is the same as this_cpu_read(VAR), and +PCPU(VAR) is the same as this_cpu_ptr(VAR). Also, "this_cpu_ptr(VAR)" is available. This is good with nesting expression. (STRUCT)(this_cpu_ptr(VAR))->MEMBER (However, it might be better to allow a special way to omit parentheses for thi_cpu_ptr()) And added a test script to test part of them. [1] https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/ --- Masami Hiramatsu (Google) (7): tracing/probes: Support typecast for various probe events tracing/probes: Support nested typecast tracing/probes: Support field specifier option for typecast tracing/probes: Add $current variable support tracing/probes: Add +CPU() and +PCPU() dereference method to fetcharg tracing/probes: Support reserved this_cpu_ptr() method tracing/probes: Add a new testcase for BTF typecasts Documentation/trace/eprobetrace.rst | 11 + Documentation/trace/fprobetrace.rst | 11 + Documentation/trace/kprobetrace.rst | 12 + kernel/trace/trace.c | 6 kernel/trace/trace_probe.c | 312 +++++++++++++++----- kernel/trace/trace_probe.h | 12 + kernel/trace/trace_probe_tmpl.h | 33 ++ samples/trace_events/trace-events-sample.c | 38 ++ samples/trace_events/trace-events-sample.h | 34 ++ .../ftrace/test.d/dynevent/btf_probe_event.tc | 52 +++ 10 files changed, 422 insertions(+), 99 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/btf_probe_event.tc -- Signature